1. Field of the Invention
The invention relates generally to audio sound recording/reproducing apparatuses, and more specifically to an audio sound recording/reproducing apparatus for converting an analog signal obtained from a microphone or the like into a digital signal for recording in a semiconductor memory, converting a digital signal recorded in the semiconductor memory into an analog signal at the time of reproduction, and outputting the converted signal as an audio sound through a speaker or the like.
2. Description of the Related Art
Among audio sound recording/reproducing apparatuses, cassette tape recorders are generally known which utilize magnetic tapes such as cassette tapes. A cassette tape recorder has advantages that a magnetic tape which is a recording medium is not expensive, recording/reproducing for a long period of time is possible, etc. It is difficult however to reduce the size and volume of such a cassette tape recorder, because the apparatus needs a running mechanism for running a magnetic tape, the noise and trouble frequency of such a running mechanism are large, and a long period of time is necessary for accessing (fast forwarding, rewinding) at the time of program search (the head portion of a program is searched and brought to the position for reproduction).
The machine for noting oral statements (such as a dictating machine) can record voice sound for a plurality of segments, and if necessary, can record information corresponding to a certain segment together with a mark for retrieval so as to aid a person to reproduce and note the information. For instance, when recording a certain document using the machine, if one desires his/her secretary to type the document later, he/she records a mark for retrieval (I mark 54) as shown in FIG. 10 (a). Subsequently he/she dictates "type this document" (the recorded portion will be referred to as an instruction portion 55). Then, the continuation of document 53 is recorded, and finally a document mark (D mark) 56 for retrieval is recorded.
Such recording permits his/her secretary to retrieve the I mark 54 recorded on a magnetic tape 51 and listen to the instruction of the dictator subsequently recorded. Based on the instruction, the secretary retrieves the document mark 52 and types out the document 53 reproducing it from the beginning. At that time, the instruction portion 55 is skipped.
If the dictator wants to duplicate the content of the magnetic tape 51 on another magnetic tape and hand it to the secretary, for example, in the case of using the dictating machine formed of a master machine 58 and a slave machine 57, as shown in FIG. 11, a process will be necessary which includes in order (1) taking out the recorded magnetic tape 51 from the slave machine 57, (2) setting it in the master machine 58, (3) duplicating the content of magnetic tape 51 on a magnetic tape 59, and (4) returning the magnetic tape 51 to the slave machine 57.
As described above, in the case of the dictating machine, it takes time for retrieval and the duplicating process is cumbersome.
Accordingly, in recent years, audio sound recording/reproducing apparatuses having a semiconductor memory in place of a magnetic tape have been developed in order to solve the above-stated problem. More specifically, in an audio sound recording/reproducing apparatus utilizing a semiconductor memory, since the accessing speed is reduced to the order of .mu.s, search of a program, for example, is instantaneously completed. Since a running mechanism is not required, it will be easier to reduce the size and volume of the apparatus. The apparatus will also be free from noise created by the running mechanism.
Although time for operation is reduced in a conventional audio sound recording/reproducing apparatus utilizing a semiconductor memory as described above, operation for retrieval of documents and instruction information from the audio sound recording area is still necessary.